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Plant Profiles

Today in the Garden of a Lifetime: Cornelian Cherry in Bloom

This year, the first day of Spring brought the last snow of Winter. With nighttime temperatures only in the high twenties Fahrenheit, and touching the forties by the afternoon, Spring was back in force—and full color—by mid-day.

Snow the last half of March? Not real news here in New England. Rather, look at this morning's snow-capped flowers of Cornelian cherry, which have been out for a week already. When I first profiled this young tree when it was in full flower in Spring of 2015, that post was in early May.

Plants perform in response to prevailing conditions, not in spite of them. If this Cornus mas 'Variegata' is in flower in 2016 six weeks earlier than it was in 2015, Spring itself must be six weeks earlier this year, too.

The big news, then, really is that the last snow of the 2015-16 season—not just snow fall, but snow visible anywhere in my garden, on the ground or on shrubs and trees—was only an inch or two that melted by noon on the first day of Spring. On the first day of Spring in 2015, there were still two feet of snow on the ground in Boston, and a foot or more here. The last piles at a famous "snow farm" in Boston didn't fully melt until mid-Summer.

To this plant geek, the picture conveys even bigger news and, appropriately, it's Cornelian-cherry-centric. Look at the enlarged portion, below: There are flowers at the very tip of this stem. Last Spring, there were no flowers higher than a foot and more below the (then) tip.

Last Spring, I hypothesized that stems didn't display flowers until their second Spring, and that the long tip growth was experiencing just its first Spring. Remember, also, that early-blooming woody plants form their buds in part or in full the previous Fall. If the very tips of stems are bearing flowers this Spring, that means that even the very tips of last year's new growth—the newest of the new growth, in other words—were still able to form flower buds before Winter dormancy descended.

It sure wasn't the young age of the stems themselves that had delayed bud formation the year before. Rather, it was the young age of the tree overall. My variegated cornelian cherries were propagated from cuttings, and they were probably yearlings at planting. Last Spring was only their second ever, and this is their third. Last year's scattering of flowers was just the warm-up when there wasn't any wood older than three years. Now there is, and flowers are being produced up and down their full four-foot lengths.

So, it seems that stems of Cornus mas can continue to produce flowers for some years, not just their first or second ones. In late Winter and early Spring in any New England garden, flowers of any size and quantity are welcome. It's only good news that a given plant can produce all the more early-season flowers because both its older and newer wood continues to bear them.

In the same introductory article on Cornus mas 'Variegata', I pointed out the showy burgundy color and length of the tree's youngest twigs. I'll follow the growth of the trees now that they have matured enough to be floriferous top-to-bottom, newest wood to oldest. Could they be pruned in early Spring—every Spring—and yet still have time for resultant new stems to mature and set buds for the following Spring? Or would those resultant twigs grow unusually long, as would be typical for growth formed in response to pruning, and also need an extra year to settle down and form buds? In that case, the trade-off would be lengthy colorful twigs at the perimeters of the canopies, but still some proportion of flowers within.

The subtleties and opportunities for best-practice handling of Cornelian cherry are likely to become apparent only slowly, and over years to come. That the wonders of even one plant in a garden can reveal themselves fully only over the course of many years is today's best news of all.

Here's how to grow Cornus mas, itself. The hardiness and handling of Cornus mas 'Variegata' are similar, with these exceptions in its culture: The variegated foliage is less tolerant of strong sun and drought stress than that of the all-green species. Site 'Variegata' in soil that is definitely moisture retentive; even so, a thick mulch will further enhance the soil's ability to retain moisture as well as remain cooler and, thus, less able to evaporate water. Further, site where the tree receives some shade beginning in mid-day.